Determine the pH of a 0,050M solution of lactic acid, CH3CH(OH)COOH (ka = 1.4x10^-4) and delta Grxn^o at 25 degrees C.

Determine pH and delta Grxn^o at 25 degrees C

I'm having trouble on getting started.

1 answer

Let's call lactic acid HL.
.......HL --> H^+ + L^-
I.....0.05....0.....0
C.....-x......x.....x
E.....0.05-x..x.....x

Substitute the E line into Ka expression and solve for x = (H^+), then convert to pH.
dG = -RTlnKa